The overall voter turnout in the by-election was 55%, down from 63% in the last general election.

Analysis

By Gareth GordonPolitical correspondent, BBC Northern Ireland

All the parties will take some heart from Mid Ulster, the by-election with one winner but no real losers.

Sinn Fein will take the win, albeit with a vote down by just over 5% for the new MP Francie Molloy.

His predecessor Martin McGuinness blamed complacency in his party's voters because the media wrote off the challengers.

The unionist parties believe the controversial plan to stand aside and back an agreed candidate, in Nigel Lutton, worked - increasing the combined unionist vote to just over 34%.

Although he came third, the SDLP's Patsy McGlone succeeded in increasing his party's actual vote in a reduced overall poll.

And in the Alliance's first election since the flag row began, Eric Bullick increased its vote from 397 to 487.

'Hard act to follow'

Before the poll was called, Mr Molloy had been deputy speaker at the Northern Ireland Assembly.

Sinn Fein MPs have a long-standing abstentionist policy from Westminster, with its other four current MPs opting not to sit in the House of Commons, but continuing to represent their constituents by lobbying the government.

After being elected, Mr Molloy said: "I would like to thank my colleague and comrade Martin McGuinness for the work that he has done over the last 15 years in moving Mid Ulster forward.

"Martin will be a hard act to follow, I understand that. But we will try our best to do that, we will continue to build the process within it and work with everyone," he said.

"I want to represent all the people of Mid Ulster, not just those who actually voted for me, not just the Sinn Fein support within the area, but all the people of Mid Ulster."

Murder allegations

The election pitted the agreed unionist candidate, Mr Lutton - whose father was killed by the IRA - against Mr Molloy.

The Sinn Fein candidate had previously been accused of being a suspect in the murder, by the DUP MP David Simpson, who used parliamentary privilege to make the allegation.

Mr Molloy vehemently denied the claims, challenging Mr Simpson to repeat them without the legal protection afforded by Parliament.

After the result was announced, Mr Lutton did not shake hands with the new MP, but BBC political correspondent, Gareth Gordon, said the pair had "exchanged brief pleasantries" in the counting hall.

Mr Lutton, who works as an undertaker, was announced as the only unionist candidate after the DUP, UUP and TUV agreed to stand aside in an attempt to consolidate the unionist vote.

On the night he polled 599 fewer votes than the combined total of the three unionist candidates in the 2010 general election.

'Relieved'

However he achieved 34% of the vote, an increase of 2% on the previous unionist share of the vote in the constituency.

The DUP and UUP both hailed his performance as a success.

Mr Lutton said he was "relieved and humbled by the result".

"As a nobody coming in, I wasn't expecting to increase the unionist vote," he said.

He told journalists that someone in the counting hall had made him laugh by describing him as the "undertaker who resurrected unionism".

Image caption
Nigel Lutton's performance was hailed as a success by the UUP and DUP

Mr Lutton's candidacy caused controversy within the UUP, resulting in the lost of two of its high profile MLAs.

Basil McCrea and John McCallister both resigned from the UUP last month, objected to their party's electoral pact with the DUP.

Unionist cooperation

UUP leader Mike Nesbitt said Mr Lutton was an "agreed" unionist candidate but said the move should not be described as "unionist unity".

"I always looked at this as an experiment. We'll go away and look at the result in much more detail and then we'll think about the implications going forward," he said.

"We're a long way from the next scheduled election which is Europe and I can think of ways in which we could clearly cooperate.

"We have Jim Nicholson already standing. I would be more than happy to recommend every Ulster Unionist voter to give a second preference to the DUP and we'd hope the same thing would come back the other way. I think that's a very sensible next step in cooperation, Mr Nesbitt added.

The DUP's Arlene Foster hailed the increase in unionism's share of the vote in Mid Ulster.

"As unionism in the west is growing again, thanks to this man [Nigel Lutton], and the cooperation that has happened in this election, I think we should send out a very confident message to unionism that we can go forward from this and I'm hoping that's exactly what we will do," Mrs Foster said.

Flag decision

Despite a reduced overall turnout, the SDLP's Patsy McGlone increased the SDLP's vote by about 650.

The Alliance candidate, teacher Eric Bullick, said he had increased his party's share of the vote by 23% since the last general election, polling 487 votes - up from 398 votes three years ago.

The by-election was the first time Alliance has faced the electorate since Belfast City Council took a controversial decision to restrict the flying of the union flag at the city hall last December.

Mr McGuinness claimed media coverage of the by-election had played a part in the drop in Sinn Fein's majority.

'Complacency'

"I would have preferred if the media had said 'this is going to be a close contest', but the media didn't say that," the deputy first minister said.

"The media said 'Francie Molloy is home in a boat, Nigel Lutton has no prospect whatsoever of winning the election'. And I think a certain amount of complacency sets in, but for us it was a tremendous result."